Time-interleaving sensing scheme for pseudo dual-port memory

ABSTRACT

The present invention provides a pseudo dual-port memory. The pseudo dual-port memory includes a single-port memory, a multiplexer, a timing control circuit and an output circuit. The multiplexer is configured to sequentially output a first address and a second address to the single-port memory. The output circuit is configured to receive output data from the single-port memory to generate a first reading result corresponding to the first address and a second reading result corresponding to the second address. The output circuit includes a first sense amplifier and a second sense amplifier, wherein the first sense amplifier receives the output data to generate first data serving as the first reading result according to a first control signal, and the second sense amplifier receives the output data to generate second data serving as the second reading result according to a second control signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority of U.S. Provisional Application No.63/010,715, filed on Apr. 16, 2020, which is included herein byreference in its entirety.

BACKGROUND

A dual-port memory handles two operations such as two read operationswithin a single clock cycle. A dual-port memory typically includes twoports operating with an array of memory cells, which may besimultaneously accessed from both ports. In order to reduce the areaoccupied by memory, a pseudo dual-port memory is used. The pseudodual-port memory is designed to use a time-interleaving mechanism toperform two operations upon the single-port memory within a single clockcycle. For example, in a clock cycle, the pseudo dual-port memory mayperform a first read operation, and then, perform a second readoperation.

Taking two read operations of the conventional pseudo dual-port as anexample, a sense amplifier is enabled twice within a single clock signalto output two reading results, respectively, and the two reading resultsare temporarily stored in two latches, respectively. Each latch iscontrolled by a corresponding control signal to output the readingresult in an appropriate time. However, the control signals of the senseamplifier and the two latches may suffer a racing issue.

SUMMARY

It is therefore an objective of the present invention to provide apseudo dual-port memory, which is more robust and efficient, to solvethe above-mentioned problems.

According to one embodiment of the present invention, a pseudo dual-portmemory is disclosed. The pseudo dual-port memory comprises a single-portmemory, a multiplexer, a timing control circuit and an output circuit.The multiplexer is configured to receive a first address and a secondaddress, and output one of the first address and the second address tothe single-port memory. The timing control circuit is configured togenerate a multiplexer control signal to control the multiplexer tosequentially output the first address and the second address to thesingle-port memory. The output circuit is configured to receive outputdata from the single-port memory to generate a first reading resultcorresponding to the first address and a second reading resultcorresponding to the second address. In addition, the output circuitcomprises a sense amplifier and a demultiplexer. The sense amplifier isconfigured to receive the output data from the single-port memory togenerate data according to a control signal, wherein the control signalis generated according to a first control signal and a second controlsignal generated by the timing control circuit. The demultiplexer isconfigured to output the data to a first latch when the first controlsignal has an enable state, and output the data to a second latch whenthe second control signal has the enable state, wherein the data storedin the first latch serves as the first reading result, and the datastored in the second latch serves as the second reading result.

According to another embodiment of the present invention, a pseudodual-port memory is disclosed. The pseudo dual-port memory comprises asingle-port memory, a multiplexer, a timing control circuit and anoutput circuit. The multiplexer is configured to receive a first addressand a second address, and output one of the first address and the secondaddress to the single-port memory. The timing control circuit isconfigured to generate a multiplexer control signal to control themultiplexer to sequentially output the first address and the secondaddress to the single-port memory. The output circuit is configured toreceive output data from the single-port memory to generate a firstreading result corresponding to the first address and a second readingresult corresponding to the second address. In addition, the outputcircuit comprises a first sense amplifier and a second sense amplifier.The first sense amplifier is configured to receive the output data fromthe single-port memory to generate first data to a first latch accordingto a first control signal, wherein the first data stored in the firstlatch serves as the first reading result. The second sense amplifier isconfigured to receive the output data from the single-port memory togenerate second data to a second latch according to a second controlsignal, wherein the second data stored in the second latch serves as thesecond reading result.

According to another embodiment of the present invention, a controlmethod of a pseudo dual-port memory is disclosed, wherein the pseudodual-port memory comprises a single-port memory, a multiplexer and anoutput circuit: The multiplexer is configured to receive a first addressand a second address, and output one of the first address and the secondaddress to the single-port memory. The output circuit comprises a firstsense amplifier and a second amplifier. The control method comprises thesteps of: in a first half of a clock cycle of the pseudo dual-portmemory: and controlling the multiplexer to input the first address tothe single-port memory; enabling the first sense amplifier to receiveoutput data of the single-port memory to generate first data serving asa first reading result corresponding to the first address; and in asecond half of the clock cycle of the pseudo dual-port memory:controlling the multiplexer to input the second address to thesingle-port memory; and enabling the second sense amplifier to receivethe output data of the single-port memory to generate second dataserving as a second reading result corresponding to the first address.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a pseudo dual-port memory according toone embodiment of the present invention.

FIG. 2 shows a circuit within part of the single port memory and acircuit within part of the output circuit according to one embodiment ofthe present invention.

FIG. 3 shows the sense amplifier according to one embodiment of thepresent invention.

FIG. 4 shows a timing diagram of some signals shown in FIG. 2 and FIG. 3according to one embodiment of the present invention.

FIG. 5 shows a circuit within part of the single port memory and acircuit within part of the output circuit according to anotherembodiment of the present invention.

FIG. 6 shows a timing diagram of some signals shown in FIG. 5 and FIG. 3according to one embodiment of the present invention.

DETAILED DESCRIPTION

Certain terms are used throughout the following description and claimsto refer to particular system components. As one skilled in the art willappreciate, manufacturers may refer to a component by different names.This document does not intend to distinguish between components thatdiffer in name but not function. In the following discussion and in theclaims, the terms “including” and “comprising” are used in an open-endedfashion, and thus should be interpreted to mean “including, but notlimited to . . . ”. The terms “couple” and “couples” are intended tomean either an indirect or a direct electrical connection. Thus, if afirst device couples to a second device, that connection may be througha direct electrical connection, or through an indirect electricalconnection via other devices and connections.

FIG. 1 is a diagram illustrating a pseudo dual-port memory 100 accordingto one embodiment of the present invention. As shown in FIG. 1 , thepseudo dual-port memory 100 comprises a single-port memory 110, amultiplexer 120, a timing control circuit 130 and an output circuit 140.The pseudo dual-port memory 100 is designed to use a time-interleavingmechanism to perform two operations upon the single-port memory 110within a single clock cycle. For example, FIG. 1 shows that two readoperations are performed within one cycle (e.g., ‘1T’) of a clock signalCK. In this embodiment, the pseudo dual-port memory 100 is a pseudodual-port static random access memory (SRAM), that is the single-portmemory 110 comprises a plurality of SRAM cells.

In the operation of the pseudo dual-port memory 100, the multiplexer 120may receive two addresses A_adr and B_adr, and in a first half of aclock cycle, the timing control circuit 130 generates a multiplexercontrol signal to control the multiplexer 120 to output the addressA_adr to the single-port memory 110, for the single-port memory 110 toselect one memory cell corresponding to the address A_adr to generate anoutput data to the output circuit 140, then the output circuit 140outputs a reading result ADO according to the output data. Then, in asecond half of the clock cycle, the timing control circuit 130 generatesthe multiplexer control signal to control the multiplexer 120 to outputthe address B_adr to the single-port memory 110, for the single-portmemory 110 to select one memory cell corresponding to the address B_adrto generate an output data to the output circuit 140, then the outputcircuit 140 outputs a reading result BDO according to the output data.By using this time-interleaving mechanism, the pseudo dual-port memory100 can perform two read operations within the single clock cycle tooutput two reading results ADO and BDO sequentially.

FIG. 2 shows a circuit 210 within part of the single port memory 110 anda circuit 220 within part of the output circuit 140 according to oneembodiment of the present invention. As shown in FIG. 2 , thesingle-port memory 110 comprises a memory cell array, each memory cellis used to store one bit. The circuit 210 shows some memory cellsbelonging to a complementary bit line pair including BL and BLB, andperpendicular to the bit lines are word lines such as WL_(i), WL_(i+1).The circuit 220 within the output circuit 140 is coupled to onecomplementary bit line pair such as BL and BLB, and the circuit 220 isconfigured to get data from the bit lines BL/BLB to generate the tworeading results ADO and BDO.

Specifically, the circuit 220 comprises a sense amplifier (SA) 222, ademultiplexer 226, an OR gate and two latches 228 and 229. FIG. 3 showsthe sense amplifier 222 according to one embodiment of the presentinvention, wherein the sense amplifier 220 comprises transistors M1-M11,wherein the transistor M1 is controlled by a control signal SAE, thetransistors M4 and M11 are controlled by a signal DLEQ, the transistorsM5 and M10 are controlled by a signal PBG that indicates a readoperation when set to logic low, the transistors M6 and M9 arecontrolled by a pre-charge signal PRE. The sense amplifier 220 isconfigured to receive signals from the bit lines BL and BLB to generatesignals DL and DLB to the following circuit. Because the operation ofthe sense amplifier 220 is known by a person skilled in the art, thedetailed descriptions about the transistors M1-M11 are omitted here.FIG. 4 shows a timing diagram of some signals within the circuit 210 andthe circuit 220 according to one embodiment of the present invention.Referring to FIGS. 1-4 together, regarding the operation of the circuit210 and the circuit 220, the timing control circuit 130 generates afirst control signal A_SAE and a second control signal B_SAE to thecircuit 220, wherein the first control signal A_SAE is used to controlthe circuit 220 to generate the reading result ADO corresponding to thefirst read operation, and the second control signal B_SAE is used tocontrol the circuit 220 to generate the reading result BDO correspondingto the second read operation. In detail, in a first half of a clockcycle, the timing control circuit 130 generates a multiplexer controlsignal to control the multiplexer 120 to output the address A_adr to thesingle-port memory 110, and the single-port memory 110 selects onememory cell corresponding to the address A_adr to generate output dataat the bit lines BL and BLB. Then, the timing control circuit 130generates the first control signal A_SAE having the enable state, andthe OR gate 224 receives the first control signal A_SAE to generate thecontrol signal SAE having the enable state to control the senseamplifier 222 to generate signals DL and DLB. At this time, thedemultiplexer 226 is controlled by the first control signal A_SAE havingthe enable state to output data A_GBL (i.e., signals DL and DLB) intothe latch 228, wherein the data stored in the latch 228 serves as thereading result ADO. Then, in a second half of a clock cycle, the timingcontrol circuit 130 generates the multiplexer control signal to controlthe multiplexer 120 to output the address B_adr to the single-portmemory 110, and the single-port memory 110 selects one memory cellcorresponding to the address B_adr to generate output data at the bitlines BL and BLB. Then, the timing control circuit 130 generates thesecond control signal B_SAE having the enable state, and the OR gate 224receives the second control signal B_SAE to generate the control signalSAE having the enable state to control the sense amplifier 222 togenerate signals DL and DLB. At this time, the demultiplexer 226 iscontrolled by the second control signal B_SAE having the enable state tooutput data B_GBL (i.e., signals DL and DLB) into the latch 229, whereinthe data stored in the latch 229 serves as the reading result BDO.

In light of above, because only the first control signal A_SAE and thesecond control signal B_SAE are used to control the sense amplifier 222and the demultiplexer 226, this new design of the circuit 220 does nothave racing issue occurred in the previous design.

In the embodiment shown in FIG. 2 , however, the timing is dominated bythe pre-charging of the signal DL/DLB, so the efficiency may beinfluenced. Specifically, the B-port is triggered after the signal DLBis in pre-charging, so a larger setup time (i.e., ‘ST’ shown in FIG. 4 )is required from A-port to B-port, where the A-port indicates the readoperation corresponding to the first half of the clock cycle, and theB-port indicates the read operation corresponding to the second half ofthe clock cycle. To overcome this problem, FIG. 5 shows a circuit 510within part of the single port memory 110 and a circuit 520 within partof the output circuit 140 according to another embodiment of the presentinvention. As shown in FIG. 5 , the single-port memory 110 comprises amemory cell array, each memory cell is used to store one bit. Thecircuit 510 shows some memory cells belonging to a complementary bitline pair including BL and BLB, and perpendicular to the bit lines areword lines such as WL_(i), WL_(i+1). The circuit 520 within the outputcircuit 140 is coupled to one complementary bit line pair such as BL andBLB, and the circuit 520 is configured to get data from the bit linesBL/BLB to generate the two reading results ADO and BDO.

Specifically, the circuit 520 comprises two sense amplifiers 522 and524, and two latches 526 and 528, wherein the each of the senseamplifiers 522 and 524 may have the structure shown in FIG. 3 . FIG. 6shows a timing diagram of some signals within the circuit 510 and thecircuit 520. Referring to FIGS. 1,5 and 6 together, regarding theoperation of the circuit 510 and the circuit 520, in a first half of aclock cycle, the timing control circuit 130 generates a multiplexercontrol signal to control the multiplexer 120 to output the addressA_adr to the single-port memory 110, and the single-port memory 110selects one memory cell corresponding to the address A_adr to generateoutput data at the bit lines BL and BLB. Then, the timing controlcircuit 130 generates the first control signal A_SAE having the enablestate to control the sense amplifier 522 to generate data A_GBL (i.e.,the signals DL and DLB, ‘A_GLB’ shown in FIG. 6 ) to the latch 526,wherein the data stored in the latch 526 serves as the reading resultADO; meanwhile, the second control signal B_SAE does not have the enablestate, so that the sense amplifier 524 does not output any valid datawhen the sense amplifier 522 is enabled. Then, in a second half of theclock cycle, the timing control circuit 130 generates the multiplexercontrol signal to control the multiplexer 120 to output the addressB_adr to the single-port memory 110, and the single-port memory 110selects one memory cell corresponding to the address B_adr to generateoutput data at the bit lines BL and BLB. Then, the timing controlcircuit 130 generates the second control signal B_SAE having the enablestate to control the sense amplifier 524 to generate data B_GBL (i.e.,the signals DL and DLB, ‘B_GLB’ shown in FIG. 6 ) to the latch 528,wherein the data stored in the latch 528 serves as the reading resultBDO; meanwhile, the first control signal A_SAE does not have the enablestate, so that the sense amplifier 522 does not output any valid datawhen the sense amplifier 524 is enabled.

In the embodiment shown in FIG. 5 , the timing is dominated by thepre-charging of the bit lines BL/BLB, so the signal of B-port and thesignal of A-port can partially overlap as shown in FIG. 6 . Therefore,the setup time (i.e. ‘ST’ shown in FIG. 4 ) from A-port to B-port issmall, and the circuit 520 can operate in a faster speed to have betterefficiency.

Briefly summarized, in the pseudo dual-port memory of the presentinvention, the output circuit is only controlled by two control signalsA_SAE and B_SAE to receive the output data from the single-port memoryand output two reading results within a single clock cycle. Therefore,the present invention does not suffer the racing issue between manycontrol signals. In one embodiment, two sense amplifiers are designed tooutput two reading results separately in one clock cycle, to improve theefficiency of the pseudo dual-port memory.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A pseudo dual-port memory, comprising: asingle-port memory; a multiplexer, configured to receive a first addressand a second address, and output one of the first address and the secondaddress to the single-port memory; a timing control circuit, configuredto generate a multiplexer control signal to control the multiplexer tosequentially output the first address and the second address to thesingle-port memory; and an output circuit, configured to receive outputdata from the single-port memory to generate a first reading resultcorresponding to the first address and a second reading resultcorresponding to the second address; and the output circuit comprises: asense amplifier, configured to receive the output data from thesingle-port memory to generate data according to a control signal,wherein the control signal is generated according to a first controlsignal and a second control signal generated by the timing controlcircuit; and a demultiplexer, coupled to the sense amplifier, configuredto output the data to a first latch when the first control signal has anenable state, and output the data to a second latch when the secondcontrol signal has the enable state, wherein the data stored in thefirst latch serves as the first reading result, and the data stored inthe second latch serves as the second reading result; wherein thedemultiplexer is controlled by both the first control signal and thesecond control signal, and when the first control signal has an enablestate, the second control signal does not have the enable state; andwhen the second control signal has the enable state, the first controlsignal does not have the enable state.
 2. The pseudo dual-port memory ofclaim 1, wherein when each one of the first control signal and thesecond control signal has the enable state, the control signal has theenable state to enable the sense amplifier to output the data.
 3. Thepseudo dual-port memory of claim 1, wherein the pseudo dual-port memoryis a pseudo dual-port static random access memory.
 4. The pseudodual-port memory of claim 1, wherein the timing control circuitgenerates the multiplexer control signal to control the multiplexer tosequentially output the first address and the second address to thesingle-port memory within a clock cycle, and the timing control circuitfurther generates the first control signal and the second control signalto sequentially enable the sense amplifier to output the data of thefirst reading result and the second reading result.
 5. The pseudodual-port memory of claim 4, wherein in a first half of the clock cycle,the timing control circuit generates the multiplexer control signal tocontrol the multiplexer to output the first address to the single-portmemory; and in a second half of the clock cycle, the timing controlcircuit generates the multiplexer control signal to control themultiplexer to output the second address to the single-port memory. 6.The pseudo dual-port memory of claim 4, wherein the timing controlcircuit generates the first control signal and the second control signalto sequentially enable the sense amplifier to output the data of thefirst reading result and the second reading result within the clockcycle.
 7. The pseudo dual-port memory of claim 6, wherein in a firsthalf of the clock cycle, the timing control circuit generates themultiplexer control signal to control the multiplexer to output thefirst address to the single-port memory, and the timing control circuitgenerates the first control signal to enable the sense amplifier tooutput the data of the first reading result; and in a second half of theclock cycle, the timing control circuit generates the multiplexercontrol signal to control the multiplexer to output the second addressto the single-port memory, and the timing control circuit generates thesecond control signal to enable the sense amplifier to output the dataof the second reading result.
 8. The pseudo dual-port memory of claim 1,wherein the output circuit further comprises an OR gate, and the OR gatereceives the first control signal and the second control signal togenerate the control signal to control the sense amplifier.
 9. Thepseudo dual-port memory of claim 8, wherein both the OR gate and thedemultiplexer receive are directly controlled by the first controlsignal and the second control signal.
 10. The pseudo dual-port memory ofclaim 1, wherein the control signal is generated by using the firstcontrol signal and the second control signal only.
 11. The pseudodual-port memory of claim 1, wherein the demultiplexer is onlycontrolled by the first control signal and the second control signal.12. The pseudo dual-port memory of claim 1, wherein the sense amplifierand the demultiplexer are only controlled by the first control signaland the second control signal.